Effective diffusivity of oxygen in the ash layer of Huadian oil shale semicoke
Yiqun HUANG1, Yiran LI1, Man ZHANG1, Boyu DENG1, Hao KONG1, Junfeng WANG2, Junfu LYU1, Hairui YANG1(), Lingmei WANG3()
1. Key Laboratory for Thermal Science and Power Engineering of the Ministry of Education, State Key Laboratory of Power Systems, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China 2. State Key Laboratory of Efficient and Clean Coal-fired Utility Boilers (Harbin Boiler Co., Ltd.), Harbin 150046, China 3. Department of Automation, Shanxi University, Taiyuan 030006, China
Diffusion of oxygen in the ash layer usually dominated the combustion of oil shale semicoke particles due to the high ash content. Thus, effective diffusivity of oxygen in the ash layer was a crucial parameter worthy of careful investigation. In this paper, the effective diffusivity of oxygen in the ash layer of Huadian oil shale semicoke was measured directly using an improved Wicke-Kallenbach diffusion apparatus. The experimental results showed that higher temperature would lead to a higher effective diffusivity and a thicker ash layer had the negative effect. Especially, the effective diffusivity along the direction perpendicular to bedding planes was much lower than that along the direction parallel to bedding planes. In addition, an effective diffusivity model was developed, which could be used to describe the mass transfer of oxygen in the ash layer of oil shale semicoke.
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